Do Not Purchase any Services from Xfinity-account debited $890.40 for a phone that was returned

I purchased a Samsung S8+ and did not like the device so I called to inquire about exchanging for an Iphone. I asked the representative the cost and he placed me on hold, the phone was disconnect after about 10 minutes. I received a message from my bank 30 minutes later informing me of a refund. I called Xfinity and was told that I exchanged my device and will be charged taxes plus $35 restocking fee. I requested to cancel as I only ask for information and did not authorize the exchange, I even requested that a supervisor listen to the call to confirm, of course they wouldn't. I was told that A RMA was already created and could not be stopped. The phone came and I did not open the box as I did not need it. My bank account was debited $890.40 for the Samsung as ot was not returned. I went to fedex and returned the device, track the delivery, and verified that it was returned to the warehouse 12/20/17. I called to provide tracking was and told that policy requires I allow 15 working days to be refunded. I called back after 16 days and was told to wait another 15 days and that the issue would be escalated to Tier 2, who would conatct me. I was not contacted at all and I called back on 01/19/2018, only to be told that it was escalated and it takes 20 business days. No one has a phone number for the corporate office, no supervisor is available. At this point, the only option to receive a refund is to retain legal services